This invention relates to control of radio frequency transmitters including but not limited to voice operated transmitter control (VOX).
The utility of a radio frequency transmitter often depends on a user being able to activate the transmitter, e.g. determine whether, it transmits. This may be accomplished with a "Push-to-Talk" (PTT) control often located on an associated transmitter housing or an acoustical transducer (the microphone). By actuating the PTT control a transmitter user can transmit to others and conversely, when released, the user may receive a transmission.
From time to time it may be desirable to provide transmit control in situations where the user does not always have a hand, foot, etc. available to activate the PTT control for each requisite transmission. One known solution is to provide a voice operated transmitter control (VOX) circuit that detects the presence of the user's voice and provides a VOX PTT to activate the transmitter. For various reasons practitioners have typically included manual controls with the VOX circuits.
A user actuated manual control may be included to enable the user to account for the fact that a specific VOX may not be compatible with the communications system or protocol on a particular operating frequency or that a VOX circuit may only provide acceptable performance with a headset, handset, or similar transducer configuration. In addition, the acoustic environment (level or other distribution of acoustic energy) often varies widely from one time to another or one location to another. This variation may force practitioners to include some form, often manual, of VOX sensitivity adjustment (conditions, audio level, time delays, etc., when VOX PTT will be provided) in order to provide an acceptable level of performance.
While these user adjustable controls may provide acceptable VOX performance, they often require valuable or nonexistent physical space and thus force the VOX circuits into an undesirable larger or separate physical package. Furthermore, the user will waste time while continually setting and resetting the manual controls to account for all the changing conditions.
To resolve the aforementioned needs and problems it is desirable to have an automatic VOX arrangement devoid of any additional manual actuation requirements which is adaptable to dynamic acoustical environments.